1. FIELD OF THE INVENTION
The present invention relates to the flotation of ores, especially phosphate ores, and magnesium-containing minerals, and more specifically to the use of certain esters of dicarboxylic acids as components of the collector.
2. DESCRIPTION OF THE PRIOR ART
The flotation of ores for separating valuable components from gangue is an old and largely used process. For the flotation of most of the salt-type and oxidic minerals traditionally a fatty acid type collector is used. These collectors usually contain oleic acid and are often called "oleic acid", even though some of the commercial collectors may only contain minor amounts of this particular acid. Of course, one will preferably use cheap materials for this purpose so that pure oleic acid is never used. Some usual materials are commercial oleic acid, oleic acid-containing wastes, fatty acids from tall oil, fatty acids from fish oils and the like.
In spite of the fact that the above materials are cheap per se, they do not always yield an effective flotation, when used in economically reasonable amounts, because they are lacking effectivity for some minerals.
A specific problem occurs in the case of phosphate ore which is mainly found as sedimentary rock. Relatively large amounts of fatty acid type collector have to be used for the flotation of the milled phosphate ore, sometimes even up to about 2 kg of collector per ton of ore, which amounts are large compared with the amount of fatty acid collector used in most other flotation processes. However, such large amounts are necessary in order to arrive at a sufficient recovery in the flotation. Of course, it is highly desirable to find a possibility to decrease the necessary amount of collector without adversely influencing the flotation results. Because, as mentioned already, the fatty acid type collectors are cheap materials, a decrease in their use is only economically feasible if further additives are not excessively expensive so that the total cost will not increase. Also, a decrease of the overall amount of collector would be desirable from the point of view of waste disposal.
Another specific problem occurs in the flotation of magnesium-containing minerals, for instance in sellaite and magnesite. Magnesium minerals are usually present together with calcium salts, and in the flotation of such minerals the fatty acid type collectors are much more effective for calcium than for magnesium salts. It would be highly desirable to have a collector which would float the magnesium salts as good as the calcium-containing minerals.
Furthermore, there are other cases where again excessive amounts of fatty acid type collector have to be used. An example of such a further case is the flotation of ilmenite.
An object of the present invention is to provide a collector additive which permits to cut drastically the amount of fatty acid type collector to be used.
A further object of the invention is to provide such an additive which itself is a cheap material which is harmless to the environment.
A still further object is to provide certain additives which are biodegradable.
Another object of the invention is to provide a process for floating phosphate ores with the use of a collector combination of fatty acid type collector and an efficient additive therefor.
Still another object is to provide a process for effectively floating magnesium-containing minerals with the use of a collector combination of fatty acid type collector and an efficient additive therefor.
Further objects and advantages will appear from the following description.